This disclosure relates to seismic surveys and marine-based seismic array deployment. More generally, the disclosure relates to deployment and retrieval technologies for marine-based seismic receiver and node systems, including, but not limited to, towed seismic arrays, autonomous ocean-bottom nodes (OBNs), ocean-bottom cable (OBCs), and other towed array and ocean-bottom seismic (OBS) applications.
Traditional marine-based seismic surveys typically utilize a number streamer cables towed behind a seismic survey vessel. Alternatively, a combination of towed streamers and ocean-bottom node system can be used, e.g., using technologies described in one or more of Gagliardi et al., U.S. Pat. No. 8,593,905, entitled MARINE SEISMIC SURVEYING IN ICY OR OBSTRUCTED WATERS, issued Nov. 26, 2013; Lambert et al., U.S. Pat. No. 8,730,766, entitled SEISMIC SYSTEM WITH GHOST AND MOTION REJECTION, issued May 20, 2014; Rigsby et al., U.S. Pat. No. 9,121,969, entitled POWER SAVINGS MODE FOR OCEAN BOTTOM SEISMIC DATA ACQUISITION SYSTEMS, issued Sep. 1, 2015; Roberts et al., U.S. Pat. No. 9,354,343, entitled DECLINATION COMPENSATION FOR SEISMIC SURVEY, issued May 31, 2016; and Gagliardi, et al., U.S. Pat. No. 9,535,182, entitled MARINE SEISMIC SURVEYING WITH TOWED COMPONENTS BELOW WATER SURFACE, issued Jan. 3, 2017; each of which is incorporated by reference herein, in the entirety and for all purposes.
Survey-based seismic exploration is performed by controlled emission of seismic energy using one or more seismic sources (e.g., dynamite, air guns, vibrators, etc.), and monitoring the Earth's response with seismic receiver and node systems configured to detect the reflected seismic waves, in order to create an image of the subsurface. In a typical marine seismic survey, air guns are commonly used to generate seismic energy in the form of acoustic waves, which propagate down through the water column and can penetrate the ocean floor to be reflected from subsurface structures in the survey area. The reflected energy travels back up to the seismic streamers, nodes, or other receivers, where it can be detected by hydrophones, geophones and similar seismic sensors. Scientists and engineers can then perform seismic surveys based on the acquired sensor data, utilizing seismic inversion and other wave exploration techniques to identify and map oil and gas reservoirs, salt and rock formations, and other subsurface structures of interest.
Conventional marine seismic surveys are conducted by towing the seismic sources behind a seismic vessel, along with an array of seismic streamers or other receivers. Receivers can also deployed along ocean bottom cables disposed on the seabed, or in the form of autonomous nodes deployed at a selected depth and orientation within the water column. The nodes can include a number of different pressure and particle motion sensors located in proximity to one another, for example using a hydrophone system to record scalar pressure measurements of the seismic wavefield, and a geophone array that records three-dimensional vector velocity measurements of the corresponding particle motion. Geophysical data pertaining to the wavefield can be acquired by using the sensors to observe the reflected seismic signals generated by the sources, and the signals can processed to form images representing the subsurface composition and structure of the Earth near the survey location.
Deploying and retrieving the seismic receivers and nodes is a complex and logistically challenging task, limiting the number of conventional seismic array configurations that can be used in a given survey area. These challenges tend to increase as larger numbers of increasingly complex node and receiver systems are employed. As a result, there is a need for more flexible and advanced deployment and retrieval technologies, particularly in the area of marine-based seismic receiver and node deployment, and which are not subject to the same limitations of the prior art.